Means eor variably controlling electrical instruments



Nov. 13; 1928.

A. D. CARDWELL MEANS FOR VARIABLY CONTROLLING ELECTRICAL INSTRUMENTS 2 Sheets-Sheet 1 Filed June 27, 1925 l NVENTOR x7114 0. (d/"dwell a. 463 ATTORNEY Nov. 13, 1928.

A. D. CARDWELL MEANS FOR VARIABLY CONTROLLING ELECTRICAL INSTRUMENTS Filed June 27, 1925 Patented Nov. 13,1928.

UNlTED STATES PATENT OFFICE.

ALLEN D. CARDWELL, OF ROCKVILLE CENTER, NEW YORK.

MEANS FOR VARIABLY CONTROLLING ELECTRICAL INSTRUMENTS.

Application filed June 27, 1925. Serial No 39,997.

In a co-pending application I have set of the controlling member may be given to forth improvcn'icnts in electrical instruments the movable element according to the char-- embodying complemcntal elements movable acteristics, requirements and constants of relatively one to another and a control the circuit to be controlled. member for the movable element, with In ,the example of my invention illusmeans operatively connecting the controlling trated in the accompanying drawings I promembcr with the movable element. for movvideanelectrical instrument such as a variing the latter relatively to the other element able air: condenser, having a stationary eleof the'instrument in such a way that for, mentand a, movable elementrespectively 10 given movements of the controlling. membcr' cqmpfisiiigspaced plates, the'movable elethe constants of thecircuitof the instrument ment having a shaft for rotating thesame, will be changed in conformity with the acontrolling member operative independent movement of the controlling member. In of the movable element and journaled con other words,-the arrangement is such. that centric therewith, an arm connected: with 15 when the controlling. member is given a said shaft, a stationary cam plate, a rotauniform movement ofi consta'nt ,character, tivecam plate connected with thecontrolling .-,or of equalchanges vor distances, they or I member,,whereby the cams 'or cam grooves able clement oftheinstlr'unient wil-Lhe moved offsaid plates mayhassume different angular in a moreor less variable manner to effect positions. relativelyto one another, and changes in the constantsio f the circuit to means cooperative between the arm and the conform wit-l1 a uniform wave length of, the. cant plates for causing.operation of the movcircuit, or to conform with a uniform fro able'element in accordance with the relative qucncy variation of a. circuit, or to conangular relation of the cams or cam grooves form with a uniformlogarithmic change in; respecting one another for imparting to the the circuit, applicable rin electrical instru- Y movableelement desired angular movements ments such as variable aircondensers,vari-v respecting its complementary, member deable, inductances, such as, variometers, varirived'from'g'iven angular rotary movements able couplers, such as.vari o-couplers, and offthe controlling member.

variable resistances, such, aslr hcostats; hfy inventionalso comprises novel details 30 An object of my invention to'provide of; improvement thatflwill be more fully simple and improved meansoperativelyrcon hereinafterset forth and then pointedout in,

ne-cting the controlling-member with:the, theclaims.

movable element of an eleotrical instruiiient: li'efereiice is to he had to the accompany of the class before set forth insuclna way: l mg "drawings forming a part hereof, 35 that the movable element of; the instrument wherein f a may be given more or lessfinorement relas ig; ol-is a face View illustrating a panel tively to. a giyen extento f movement of the inf eon'nection with which my;improvementcontrolling member, which latter may be is '.app li'ed; I f rotated 360, or approximatelyso, for 186 Fig. 2 is a vertical section on line 2, 2, 40 rotation of the movable element, or ape in Fig. '1; proximately so, or in any .other desired fig: 13 is a detail perspective view of the ratio, with the controlling element. located actuating arm;

concentrically with respect to the movable Fig, 4 is a cross section through Fig. 3;

clement, whereby for substantially what may Fig. .5 is a partly broken face view of; be called coarse movement ofthe controlling parts in the position shown in Fig. 1, the member relatively fine movements of the controlling member or dial being omitted; Il10"i1l)l'3 element may be given at some por- Fig. 6 is a section on line 6, 6, in Fig. tions or" its operation and relatively coarse 5, illustrating also the controlling member or more extensive movement-sot the movable or dial; 50 element may be given at other points of its F ig. 7 is aface view illustrating the sta rotation, and other movements equal to or tionary cam plate; variable respecting the extent of movement Fig, 8 is' an inverted face view of the secured to shaft- Sio'fth ei novable element movable cam plate that is represented partly broken in Fig. 5;

t Fig. 9 is a view illustrating the cam plates in a position different from Fig. 5;

Fig. 10 illustrates-the rot-ative cam plate in the position it assumes when the actuating arm has been moved 180 from the position snown in- Fig. 5; and

Fig. 11 is a perspective detail of washer.

Similar numerals of reference indicate corresponding parts in the several views.

I have illustrated my improvements in connection with a variable air condenser 1, which may be'of any well known construction, having a stationary element 2 comprisin spaced plates 3 and a IDOVQlJlG ClBmQHt or rotor 4" having, spaced plates 5 carried by a shaft 6. In the example'illustr'ated the condenser is provided "with" semi c'ir cula'r movable plates o'wliereby there is afforded an approximately unifolm'va-riation of capacity for uniform angular 'inbveiiients of shaft- 6 throughout l8O'rot ation, and such plates will admitja"maxilnumcapacity for a given bvr-ananmension of condenser, since the full radii bi throtbr. platesare efiec tivef In Figs. 2 zin'd j5 the c ondenserplates are fully interleaved as in ftlll capacity}; (in dotted lin's)',' said plates bein represented in Fig.- 9 inparti'al pdhtio ,1zmd in'Fig; 10 as at miniiuqmjc'a cirj position. In other, wo'rds',' the "condenser illustrated is of "the variety commonly called' a straight line capacity condenser.

a spring At"? is a controlling member or: what is m y cand 1?:i i 1 6 did lP 9 to be o' ierat' tltocactuate'theinovable element or rotor lrelat 'ively tq'lthe station; ary element 2E A t 8"i"ai1"attiaitii ig or rotor, as by nieansoi a scriewff9 Arm'S 'to' indicate, the angular: positions the arm 8 and the rotor on any arbitrarysc'ale. Iii' the example illustrated 180 of rotation. shaft 6fis representedlby divisions of the scale on the' pan'lfat A.; an' d theifeby' the relative positions of.t l ie movable element or rotor plates 5 with relation to the stationary plates 3 0jf the condenser'inay be determined. I provide'mea'irs for variably ment from miven'oriuniforxn movements of the controlling member or'dial'l. For such purpose I provide a stationary plate 11. which may be secured to .a panel or other support; 12. as of a radio set as by screws 12 in connection with which the condenser or electrical instrument may be supported in any suitable way as by mounting posts 2 secured to the. panel by means of the screws 12'. The'sha-ft 6 projects through Fig. 6). I p 'sembled, as indicated in Fig. 2, the cam disks an opening in the panel and through a clear. ance hole 13 in plate 11. (Fig. The plate 11 is provided with a cam g;oo .'e or raceway 14-. At 15 is a rotativc plate or dis]; provided with a cam groove or raceway it; and mounted to rotate conrcntrically with respect to the axis of the movable t-ieznent or rotor 5. and the. plate wais -provided with a hub or sleeve I"! mounted to rotate concentricall with the axis of the movable. ole

nient or rotor and. shown journalctl upon the hub or sleeve 8. I have shown a nut 1S upon hub S operative in conjunction with a spring washer 19 that surrounds said huh and bears against the hub or sleeve 17 for the purpose of retaining plate 15 springpressed toward cam plate 11. The controlling, member or dial 7 shown provided with a bore 7 enclosing the adjacent portions of parts (5 8 and 17, and with a skirt portion 7" surrounding the plates 11 and 15, (Fig. 2). Controlling member or dial 7 is rigidly connected to the cam disk 15. I have shown said parts connected by means of screw 20 carried by the controllinp mam bar and engaging: the hub 17, whereby when the controlling member'o r dial is rotated in one direct-ion or another the cam plate 15 will be correspondingly rotated. I utilize the' rotation of cam late 15 to control the rotation of the mova l'e-elem'c'nt or rotor 4 relatively. to the stationary element 2. For such'purpose I provide a movable :ncinbcr preferably in the nature of a ball 21 ada pted to operate in the cam grooves 14 and 16,

which member or ball is'guided to travel longitudinally along arm 8. wnile. causing the latter to rotate. 'lo'retain said member or ball 21 and'arin 8 the latter is provided with a longitudinal slot 8" receiving the ball,

the edges of whichislot diverge frozni the outer surface 'of the arm inwardly. in the nature of a man to. retain theball in operativeposition'inlhef'slot. The arm is shown lon itudi'nally slit at c so'that the arm may be spread to permit inscitioni ol the ball, and'the pointer. 10'is shown rc tained between lhc two p'G'rtiQns of the arni .by means of rivets 22. "The pointer is bent.

laterally 3510 -250 that its outer end may extend beyond the plates 11 and 15 and project between thelinner edge of the'controllin; member or dial 7 and the panel (see When the parts descr bed are as will be so related that the member or ball 21 will be located in the cam firooves of the disks. since such grooves at some relative points always coincide and oppose one another.

It will be observed that the cam groove '14 is of such a character as to partially surround the axis of the movable element or rotor 4 with one portion of the can! groove at 14" nearer to said axis than the other-porlUU Ill)

ti on 11 the cam groove being designed to will rotate around the axis of shaftG in acaid in causing the arm 8, and thereby the cordance With the above mentioned law as movable element or rotor, to travel at variplate is revolved through 360. Inasahle speeds. The cam groove 16 has its pormuch as the movement of ball 21 carries the tiou 16 nearer the axis of disk 15 than its arm 8 any angular movement' of hall 21 '7 portion 16 The radial distance from the about the axis of shaft 6will be imparted axis of shaft 6 is the same respecting the directly to said shaft and thereby to the termini 1 1. 16 of the grooves 14, 16 and rotor element of the control device. The also the same regarding points 14? and 16 varying positions of the ball radially from When the rotor is in the full capacity or the axis of shaft6 are permitted because of minimum capacity position respecting the the longitudinal ball race on arm 8. The stationary element 2 the cam groove 16 will position of the ball along said race does not lie upon the side of the axis of the rotor opalter the angular position of the arm 8. posite the groove 14, and when plate 15 is From the shape of curve 16 it will be seen I rotated in one direction or another the cam that a relatively large movement of cam roove 16 will be moved with the disk in plate 15 will be required in order to produce such a manner as to cause the groove 16, and comparatively small angular movement of thereby cause the ball 21, to travel corball21when the'two-cam platesarenioved respondingly, since the walls at the sides of from' the position illustrated-in -Fig 10 the cam grooves engage the ball and push clockwise; but as the cam plate 15 is -rotated' it, the ball in turn causing arm 8 to corfurther ina clo'ek'w-ise direction the'point of" respondingly rotate andthereby the movable intersection of the two curves will have a element or rotor of the condenser is cor lgreaterjangular velocitythereby causing-an respondingly actuated. In the position of increasedaot'ationof shaft- 61m.- the; same the parts shown 'in' Fig. 5 the condenser angl'llar iot-ation of cain=--plate'- 15. YVhen elements are in maximumfcapac'ity position cam plat'e15 is rotated in a'n opposite dire'c with the ball 21 en aging both the cam; tion-"or counter-clocliw ise the converse is grooves at their respective points 14 and 16% truei In*theflxample illustrated wvhen' both- If the controlling 'member'oi di'al berotated can; 'slot's' 'compris l80 "aboutthe axis of counter-cloclnyise inf'Fig. 5"the cam groove'fshaft' fi itfi's self 'eyidenb tha't a rotation of 16 will be caused to advanee'iri irate-diatribe? 360 enly ispermittedplate 15; providing of the cam groove 14' and lthereb'yjthef ball the baII Q IjiS-retain'e'd =withi 1'r'grooves 14 and 21 will be correspondin ly"iiioved "and"f16;for eta-one positi'o the"'ba'llwwill be 10.

the rotor pla tes"5"will flue iii? i catedas'illn'strated in Figg fi' at the minimum 1 direction from makijmu'rn'f io'ward "Iriini .radiaI-' points of'both'ca'm grooves andmam' mum capacity. In the 'exa inple illustratedplate 15"vvill be1')"r'ex ente 'd t'rom' further the cam groove 14 is'laid'out'gs a' full toga-5 clockwiserotation byisaid-b'alla ='=When"cam rithmic'spiral' so that 'equ'al'a'ng1ilai"pos1{ plate"'15"i"rotatied' iri 'actiuhtermlookwise tious of ball 21 in saidcam grb tit eifiom 'direction from the point illustrated in Figg increments in radius from the aaisi of groove =14and jafti'j360 rotation ofcam 6. The orbiter-je n 21 ;wi 1l icompri se 18p slot' f'lfi the balr aaywiu agaiainte'rcept the" rotation about shaft 6. Cam'groove"16,'on frotationidf 'cainfl plate 1 5 'and=' res'trict -1ts= movable plate 15, is} laidflgeese"that-the ;movement;innsngueh e remit-betruths oporbit. of ball 21 will} be'firesti'i tedi to"1 8fQ posite 'nid'ofthe' caxyslgtsgnamelyat points-110.

movement in siiclifgroovehnd faroiiiidthe im and =16"; intheflrespective carnsi axis of shaft "G ngr ne-"16 has ueen" 'Pins' 2iifprbjet point 16 will? be the, same ,rad al d1stance*valr1oi1s'form's any-"variable relati've'jangu'lar' from said axis as point 14" of can; g roovef bv'emenfi' betweeneontremag me' mber or 1.4. Intermediate positions on cam roove;"dial=7 ant1 'the eontijolledjshaftfti maybe-ae- 16 will vary'betweenihese eirtreme minlin'umf taflinedj For example if iti is requi'red that and maximum'radial dimensionsfaccordiiig a greateriotation of'plate 15 be'tlesired for to a curve which will fixthe pointoflinterf a smaller rotatiofipfshaftfi the cani'fslotlti section of the centers of'the, two cam grooves, should approach the" are "of circle with or the center of the ball rolling in such thefcenter'at lthe axis'ofslfaft 6, and if the grooves. at various points required in acdeSired mOtion'is;s '-s1ow'- as to-require -a cordance with .the angular rotation of cam verydong'slofl'lfi'the'same*m'ay be accom grroove .16 as desired. F or examp'le; if it is plislid'by having slot" 16 comprise-more required that. the movable element or rotor "than 1809'; so'that said 'slotfinayrom'prise be rotated in accordance with'the square of 540, "in "which ease; the total movement;- half of the angle of rotation of plate 15 the would'be' two' revolutions of'th'e controlling point of intersection of-the "two cam curves member-or dial"'or 720-total;f0r*180-rota- 1 v the cir'cuih; lily-improvements are: appli semicircular rotative plates .5 of the socalled straight line capacity type. Any

shape plate may be used and corresponding corrections incorporated in the shapes of the in conjunction with the difierently shaped rotor or stationary plates or other factors of the controlled element designed, for which compensation may,.-be desired. The contour of the cam grooves 14 and 16 may be-such as to cause variable rotation of the rotary element .of the electrical, instrument or condenser in conformity with given or. uniform angular; rotative. movements of the controlling member ,or dial for producing, changes inithe capacity constants of the circuit to conform avith a uniform wavelength of the circuit, or toconform .with a uniform frequency variationof the circuit, oifi to con; form with auniform logarithmicchange cablefnot only in gvariable air condensers but to the control of .variableindutptances, such as variometers, variable couplers, such. as vario-couplers, andin variable resistances, suchms .rheostats, wherein-"the angular rotation of the movable element thereof may be variable'in conformityfwith'a; given angular rotation of the .controlling-.member,or, dial. 2 i

to 100, indicated atii,

trary scale from zero. with equal divisions betweenthe minimum andimaximum The pointerlO travelswith relation to said scale and the various positionspirtl erotorclen ment can beread directly,-on .-,such'sca1e. The dial 7 is showngraduateding ftwenty divisions'between lO-and' 200,-,I'reading in a, counterclockwise idirection with theminimum and maximum positiomopposite the lubber line at,the zero position ,oi th'e, scale,- on panel 12. The equal-angular movements, of the dial 7 will represent equalincrements; of scale on such'dial, andindexpointerild, will travel from zero to. 1001011panel- 12 while-dialTis turned through; 3609;. I-Iovvever, index pointer 10- will nottravel qver= corresponding degrees of numeralson to its 1 dial for equal movement ofdial 7 but will move with increasing velocity in accordance, with the contour of the respective control:- ling cam grooves and'in conformity'with the given angular movements of the dial. The index on the dial 7 may be-so divided as to indicate equal. wave lengths, equal inless than,.'equal to, or

On panel-l2 iaii;

throughout the 180 creases, in frequency, or equal logarithmic increments, or any other units to be designated.

In accordance with the example illustrated and assuming that the rotor plates are in the position of minimum capacity and that the controlling member or dial T is rotated manually in a clockwise (.ircction (from the position of the rotor plates and pointer 10 shown in Fig.- 10), the rotation of the controlling nienibcr or dial for a given distance, say 5 on scale A, will produce a corresponding directional movement of the rotor but member.- .For each further degree of rotation of the controlling member in the same direction the rotor. 4 will be rotated at an increasing 311 1113. distance but less than the angular. distance rotated by the controlling member, so that the rotation of the rotor is yariable ,with respect to givcn or uniform angular distances of rotation of the controlling member, whichpcrmits the operator to actuate the controlling member with V relatively coarse movements for all positions along the scale with therotor actuated for distances ,respecting the stationary element according to. the required relative positi'oi1s, fv the 'movablejand stationary elements lof 'the instriiinent ivithj respect to were 1 lengthglnljocycles, or. other characteristics ,Oric nstants'of the circuit. By changing the contour. oigoneorbothcam grooves of the platesor members 11 :and 15 the movement imparted,- toltlie movable elcmentor rotor ling ,memberor dial may be I W more than given moremerits o f, th latter at any desiredposition;

organ pa by the control i si a .i

' -1. An, electrical instrument ,comprisin g T complementa l elements movable relatively 01i tofla n ot her,{a controlling memb'eri otative; i.ndepen dcntly ,o ithemovable element, ga stationary camime mb ergi seco'ndcam menn ber. rotati v e relati vely to the stationary cam memberand, connected, :ivith the controlling;

,member, for; operation thereby, an .arm connected with the movable elemenn and a' ball cooperative with said arm and with said carniirtexrribefs and movable relatively thereto ,for actuating the movable element at variable distances for given distances of rotation .of .the controlling. member for producing eq'ual changes intheelectrical circait in i which the instrument is used, the arm having guiding means for the ball, whereby rotation of the movable cam membcr will cause the ball to travelalong the arm for variably rotating the movable element in conformity with given movements of the controlling -membcr for changing the constants of the circuit.

2. An electrical instrument comprising cam grooves, to compensate for or operate: of less angular distance than the controlling ;j aving; nowdescmbed my invention what complemental elements movable relatively one to another, a controlling member rotativc independently of the movable element, a stationary cam member, a second cam member rotative relatively to the stationary cam member and connected with the controlling member for operation thereby, an arm connected with the movable element, and a ball cooperative with said arm and with said cam members and movable relatively thereto for actuating the movable element at variable distances for given distances of rotation of the controlling member for producing equal changes in the electrical circuit in which the instrument is used, the arm having a longitudinal slot receiving the ball and provided with means to retain the ball operatively along the arm, whereby rotation of the movable cam member will cause the ball to travel along the arm for variably rotating the movable element in conformity with given movements of the controlling member for changing the constants of the circuit.

3. An electrical instrument comprising complemental elements movable relatively one to another, a controlling member, a plate secured relatively to the movable element and provided with a cam groove, a second plate rotative with respect to the first named plate and provided with a cam groove opposing the first named groove in position to intersect the latter, means operatively con necting the controlling member with the second named cam plate for rotating the latter, an arm connected with the movable element, and means movably operative in said cam grooves and adapted to operate the arm in conformity with the intersecting positions of the cam grooves during rotation of the controlling member for operating the movable element variably with respect to given movements of the controlling member in such a manner that equal movements of the controlling member give equal changes in the circuit in which the instrument is used.

4. An electrical instrument comprising complemental elements movable relatively one to another, a controlling member provided with an actuating arm, a stationary plate having a cam groove extending; partially around the axis of the movable element, a plate mounted to rotate concentrically with respect to said axis and provided with a cam groove adapted to oppose the first named cam groove and to coincide therewith in different positions of the second named plate respecting the first named plate, and means cooperative wit-h said arm and movably operative in said cam grooves for actuating said arm and thereby the movable element variably with respect to given movements of the controlling member in such a manner that equal movements of the controlling member give equal changes in the circuit in which the instrument is used.

ALLEN D. CARDWELL. 

